Showing papers on "Derivatization published in 1977"
TL;DR: The possible scope of this method for analysis of other aminoglycoside antibiotics is illustrated by application to sisomicin and netilmicin.
Abstract: A procedure is described that uses high-pressure liquid chromatography for assay of gentamicin in serum. The technique involves extraction of gentamicin from serum by using a CM-Sephadex column and analysis by reverse-phase, ion-pair chromatography. Continuous-flow, post-column derivatization with o -phthaladehyde is used to form fluorescent products for detection. The possible scope of this method for analysis of other aminoglycoside antibiotics is illustrated by application to sisomicin and netilmicin.
93 citations
TL;DR: In this article, a trace enrichment technique is described that permits the use of large injection volumes of up to several millilitres, and the reproducibility of these techniques when applied to quantitations is usually below 4% and is further enhanced by using a timer-controlled valve and a continuous-displacement pumping device for injection of very large volumes.
73 citations
TL;DR: Modifications to the derivatization procedure of MacKenzie and Tenaschuk have been introduced and Amino acid analysis of beta-lactoglobulin after 6 N HCl digestion yielded results in good agreement with those obtained by the conventional ion-exchange method.
73 citations
TL;DR: In this paper, a method for the quantitative determination of aliphatic α-keto acids in urine after derivatization with o-phenylenediamine and bis(trimethylsilyl)trifluoroacetamide, α-Ketovaleric acid and α -ketocaprylic acid are used as internal standards.
62 citations
TL;DR: The well known air segmentation principle used in connection with Auto-Analyzers was applied successfully to members of the C-group of cardiac glycosides, which were separated on a reversed phase HPLC system and the improvement in the detection limit was at least 100-fold in comparison with UV detection.
60 citations
TL;DR: The specificity of this method has been demonstrated with brain tissue by simultaneous mass fragmentographic analysis and the sensitivity is comparable to that ofmass fragmentographic methods and is in the femtomole range.
51 citations
Journal Article•
TL;DR: Values for the concentrations of "apparent" hydralazine that are dependent on the pH in the derivatization step are yielded, which are explained by postulating the existence of acid-hydrolyzable conjugates of unknown structure.
Abstract: Derivatization of hydralazine in plasma under acidic conditions yields values for the concentrations of "apparent" hydralazine that are dependent on the pH in the derivatization step. The results have been explained by postulating the existence of acid-hydrolyzable conjugates of unknown structure. These metabolites appear to be present in rat and human plasma after oral dosing. Procedures have been developed for the selective analysis of hydralazine or its acid-labile conjugates, and applied to measurements of plasma concentrations in rat and man.
43 citations
TL;DR: A gas-liquid chromatographic (GLC) method has been developed for the analysis of samples containing nanogram to picogram amounts of three different types of monosaccharides, viz., aldoses, ketoses and deoxy sugars as mentioned in this paper.
40 citations
TL;DR: A high-performance liquid chromatographic method is described for measuring submicrogram quantities of dianhydrogalactitol, a promising anti-neoplastic agent, in plasma.
TL;DR: High-performance thin-layer chromatography affords a rapid, sensitive method for determination of psychopharmacologic agents in blood serum samples and neither derivatization prior to, nor color development after chromatographic separation is required to achieve sensitivity and reproducibility of determinations.
TL;DR: A comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptylines, imipramine, desipramines, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector is described.
Abstract: We describe a comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector. All these drugs are extracted and chromatographed under identical conditions. Each tertiary amine tricyclic is well resolved from its secondary amine metabolite on a mixed-phase column and the concentrations of both are determined simultaneously, without derivatization. The lower limit of sensitivity is 10 microgram/liter of plasma (2-ml sample). Analytical recoveries of the tertiary and secondary amines are 100 and 80%, respectively. Between-run CV's for all of the drugs ranged between 5 and 7%.
TL;DR: The results of a survey of derivatization techniques involving several substituted anilines are presented, and a rationale is presented for the preliminary selection of a particular derivative for application of the analysis of aniline metabolites in urine.
Abstract: A number of amines have been shown to result from metabolism of various pesticides. From an epidemiological standpoint, it may be possible to monitor human exposure to these pesticides through the excretion of their corresponding amines in urine. An investigation has been initiated to develop and apply methods of analysis of amines in human urine. The results of a survey of derivatization techniques involving several substituted anilines are presented. These include conditions for derivatization, utilizing a number of halo- and nitro- substituted reagents; electron capture and gas chromatographic properties of the derivatives; and stability of the derivatives to extraction and column chromatography for purposes of separation and cleanup. The recoveries of anilines from spiked water and urine samples at the 1.0 ppm and 0.1 ppm levels were between 85 and 90%. The advantages and disadvantages of the various derivatives and techniques are discussed and a rationale is presented for the preliminary selection of a particular derivative for application of the analysis of aniline metabolites in urine.
TL;DR: A new type of rearrangement alpha-beta-elimination of ethylene or propylene from the aliphatic sidechain, is proposed for some O-TMS quinoxalinols.
Abstract: In acidic media o-phenylenediamine and 2-oxoacids react to yield quinoxaline derivatives. On derivatization in pyridine with silylating reagents quinoxalinol-O-TMS ethers or O-TMS-ether-TMS-esters are formed exclusively as shown by gas chromatography infrared spectrometry and gas chromatography mass spectrometry. These derivatives have very favourable properties for gas chromatographic detection and quantitation of the parent 2-oxoacids. The mass spectra have characteristic fragments which facilitate easy identification. In addition, 'single ion monitoring' of all aliphatic 2-oxoacids can be performed with only three fragments at m/e 217,232 and 245. In some aspects the mass spectra resemble those of other heterocyclic compounds which contain an O-alkyl sidechain. The fragmentation mechanisms were deduced by low resolution mass spectrometry with and without deuteration, high resolution mass spectrometry and metastable ion evidence. A new type of rearrangement alpha-beta-elimination of ethylene or propylene from the aliphatic sidechain, is proposed for some O-TMS quinoxalinols.
TL;DR: A gas chromatographic micro method utilizing an organic nitrogen sentitive detector for the determination of serum theophylline is described in this paper, where the method incorporates 3-isobutyl-1-methylxanthine as the internal standard and involves extraction and off-column derivatization.
TL;DR: Two sensitive detection systems are described for the quantitative determination of a nonvolatile nitrosamine, nitrosoproline, and the HPLC fluorescence technique is approximately ten times as sensitive as the GLC method.
TL;DR: The method permits analysis of apomorphine in the presence of its two monomethyl ether metabolites, apocodesine and isoapocodeine, which are also chromatographically resolved as their heptofluorobutyrate derivatives.
TL;DR: Experiments with 5-O-desmethyl-indomethacin have demonstrated that using the described diazomethane methylation conditions no alkylation of the phenolic group occurs, allowing quantitative assay of the drug at the submicrogram level.
Journal Article•
TL;DR: The quantitative analysis of propranolol and its metabolite N-desisopropylproprol in plasma and urine is described and the recovery from plasma is 70%, with a standard deviation of +/- 4%.
TL;DR: A gas chromatographic method for the plasma assay of the anticonvulsant, sodium valproate, is described, and the between-run precision of the method indicates a variation for each sample within+/-3% of its mean value.
TL;DR: The chromatographic analytical separation of the urea test solutions was established to demonstrate the derivatization of the isocyanates and direct determination of the produced ureas from the reaction mixture.
TL;DR: The diastereomers formed from amino acid methyl esters and IIb by the N, N'-dicyclohexylcarbodiimide method were efficiently resolved on the normal phase column.
Abstract: A new method for liquid chromatographic resolution of amino acid enantiomers by the formation of diastereomers has been developed. A chiral reagent used for this purpose, (-)-α-methoxy-α-methyl-1-naphthaleneacetic acid (IIb), was readily prepared by fractionally crystallizing the (+)-α-methylbenzylamine salt. The diastereomers formed from amino acid methyl esters and IIb by the N, N'-dicyclohexylcarbodiimide method were efficiently resolved on the normal phase column.
TL;DR: Data from field desorption mass spectrometry of peptide methylation-methanolysis product mixtures are used to ascertain the number of carboxyl groups present in a peptide, identify a pyro-glutamyl N-terminus and derive peptide sequence information.
Abstract: Analysis by field desorption mass spectrometry of reaction product mixtures produced by treatment of peptides with methanol and hydrogen chloride augments significantly structural data derived by direct field desorption mass spectrometry analysis of the peptides. Analyses of data obtained by three peptides, beta-Ala-HisOH, p-Glu-Ser-GlyOH and Glu-Ser-Gly-AspOH are used for illustration. Data from field desorption mass spectrometry of peptide methylation-methanolysis product mixtures are used to (a) distinguish [M]+- from [M + H]+ in peptide field desorption mass spectrometry spectra, (b) ascertain the number of carboxyl groups present in a peptide, (c) identify a pyro-glutamyl N-terminus and (d) derive peptide sequence information. Definitive assignments of ion relationships are facilitated by use of methanol and deuteromethanol in paired experiments.
TL;DR: The aims of this study were to determine the effect of levels of various substances and reaction by-products, which are formed during hydrolysis of nucleic acids, on the derivatization and chromatography of nucleosides; and to investigate the silylation of mono- and dinucleotides.
TL;DR: A rapid, sensitive and specific high-pressure liquid chromatographic method is described for the quantitative analysis of clofibrinic acid in plasma, saliva and urine with a coefficient of variation from 1 to 6%.
TL;DR: A sensitive and selective method for the determination of the quaternary ammonium compound oxyphenonium bromide (Antrenyl), a drug with strong anticholinergic properties, in human plasma and urine is described.
01 Jan 1977-Journal of Environmental Science and Health Part B-pesticides Food Contaminants and Agricultural Wastes
TL;DR: A new gas chromatographic method reliable in the microgram range, was developed to measure ETU residues in various crops, and does not require prior derivatization of the ETU.
Abstract: A new gas chromatographic method reliable in the microgram range, was developed to measure ETU residues in various crops. Contrary to previously published procedures, this new method does not require prior derivatization of the ETU. The limit of sensitivity was shown to be 0.01 ppm using the flame photometric detector, FPD (sulfur mode, 394 nm).